Lithium battery charging

[kerplode]

Lithium batteries like to live in the 40%-80% charge range. Deep cycling them is hard on them and can reduce their life span. They don't develop memory like those garbage NiCads did, so no harm in charging them when they get to about 50%.

If you want to store on for an extended period, it's somewhat better to store them at 50% than at 100%.

[matrixcs]

lithium battery packs can be rebuilt if soldering is your thing and you can save $$$ . I have dropped a couple packs and the battery's cracked and do not hold a full charge so I sent them to recycle and bought new. I have done it both ways but I am lazier now so new was my easy out...

[brassrat]

I know the 18650 ? flashlight batteries will be destroyed if charged for too long.

[kerplode]

lithium battery packs can be rebuilt if soldering is your thing and you can save $$$.

This is dangerous if you don't know what you're doing. The cells need to be properly balanced before you bond them otherwise the unequal voltages can result in a huge inrush current between the cells that can overheat them and start a fire.

Lithium cells are no joke and should not be taken lightly.

[Randy Bohannon]

I leave all my LIon batteries IN THE TOOLS 100% of the time! Depending on the charger, the brand, and/or battery array, they do not like to stay on charger/plugged in all the time. I ruined several NICAD packs by doing that. I have left my several BOSCH LIon tools lying around for 2+ years (during China Virus times) with no damage to the tool or the battery packs. And they had 100% charge when I grabbed them to use them.

And there are many smaller tools & devices out there that the batteries are NOT removable! How do you address that?? Do you take the LIon battery out of your iPhone/Smartphone every night?

Nice thing about LIon's is when they run down, it's like falling off a cliff. They pretty much just stop and do not taper down in output like older technologies always did.

Read the owners manual on the Milwaukee, Rigid, De Walt, Ryobi, all say what I already said. Go at your own discretion. IPhones, small electric devices are disposable I don’t throw the tool away because a battery failed, I get a new battery. Little tiny batteries are not 18 -24 volt lithium batteries very different animals .

[kerplode]

Little tiny batteries are not 18 -24 volt lithium batteries very different animals .

Yeah, not really. Guess what’s in that 18-24v pack? Same thing that’s in a 350v 75kWh Tesla pack…A bunch of little tiny battery cells wired in parallel-series chains.

[gc45]

My shop is full of different Dewalt battery tools, some older 18 volt, some newer 20 volt and most all have the batt left in them and so far lasted us a good long time. My 20 volt battery grease gun gets used lots as we have both farm equipment and const equip always needing grease. Best tool ever!

[bangerjim]

This is dangerous if you don't know what you're doing. The cells need to be properly balanced before you bond them otherwise the unequal voltages can result in a huge inrush current between the cells that can overheat them and start a fire.

Lithium cells are no joke and should not be taken lightly.

SOOOOOOOOOOO true!

Do not mess with rebuilds!

[bangerjim]

Yeah, not really. Guess what’s in that 18-24v pack? Same thing that’s in a 350v 75kWh Tesla pack…A bunch of little tiny battery cells wired in parallel-series chains.

Absolutely NOT! Electric car and hybrid car batteries are made from a huge stack of ~1.5" thick rectangular cells. All lined up and series wired in a row.



My Lexus hybrid cars have that arrangement. And carry a 10-year warranty. Never had a cell go bad in over 10 years.

Tool packs are made of normally round C or D size cells wired in series to get to to the voltage needed.

[kerplode]

Notice I said Tesla battery?

Tesla batteries are comprised of multiple modules, with each module being constructed of many individual small cells…Essentially hundreds of what are basically 18650 cells.

Here’s a teardown of a Model S module:

[kerplode]

This vid details the Tesla module architecture


And this one discussed the various styles of EV cells, their trade offs, and why Tesla chose small standard cylindrical cells

[popper]

The cells need to be properly balanced before you bond them otherwise the unequal voltages can result in a huge inrush current between the cells that can overheat them and start a fire.

Actually the cell voltage needs to be balanced, if not they will reverse voltage on the lower cell and batteries DON'T LIKE reverse polarity.

[kerplode]

So driving current into the positive terminal isn't necessarily a bad thing (and doesn't really result in "reversed voltage" as you claim). This is how they are charged after all. But a controller in the charger monitors the battery and limits the maximum current into the battery to prevent drama.

The problem with parallel-bonding un-equalized cells is that the high battery will try to "charge" the low battery until the voltages equalize. Because the node connecting them can't sustain more than a trivial potential difference due to the DCR of the wire, there is nothing in this configuration to limit the current flow from the high-voltage battery to the lower-voltage battery but the internal ESRs. This is what I mean by inrush current.

In this config, the instantaneous power transfer can be well over 100W if they are very unbalanced. This much power/current will rapidly heat the batteries and can cause them to swell and or burst which can start a fire.

For a series configuration, cell balance is less critical in that it won't result in fireworks, but having them unequal will make the pack inefficient. A good pack/charger design will have the ability to rebalance the series blocks during charging. If you look at a dewalt pack, four of those pins (C1-C4) are the intermediate nodes between the 5 series elements. The charger can manipulate the voltages here to alter the charge state of the individual series elements, thus rebalancing the pack.

But for parallel elements, the voltage (and thus the charge state) balancing has to be done precisely before assembly otherwise there is a significant risk of fire.

[bangerjim]

That is exactly why when I buy the "Tesla Battery Wall" for my 8KW+ solar panel array, it will be a commercial-built unit (not homebrew in my shop!) and installed and wired in by a licensed electrical/solar contractor. Those packs are very pricy and I am hoping the price will come down drastically with the advent of new and less costly manufacturing and packaging technology.

Friends ask me, with all my electrical engineering expertise, why I do not buy a battery system out of a wrecked LEXUS and build my own. No thanks! My home is just fine without a potential fire/explosion outside on the wall!

[kerplode]

Dude, I'm with you! Even with 20 years EE experience, there's no way I would ever attempt to do a DIY home-build lithium bulk storage array. No. Way. This stuff is no joke. A Power Wall sized array contains a ridiculous amount of energy and can start a MASSIVE fire if mishandled.

Hell, it even makes me a little nervous to leave a good quality 18650 cell charging in a proper commercial charger. I don't buy cheap un-protected 18650s either.

IMHO, people are way too cavalier with these cells...

[kerplode]

And since I guess we can only talk about Ryobi batteries:
The OPs pack has bad cells and needs to be replaced.

[GOPHER SLAYER]

Moderator, I think we have found out all we need to know about lithium batteries, so I think you should put this post to rest and thanks again to all who responded. Glen

[Mal Paso]

I found this thread informative. As far as powering a house Lead Acid batteries are still much cheaper and the better quality ones last 16-18 years with care. I don't know that they have achieved that sort of life with Lithium but they probably will fairly soon.

Thanks!

[bangerjim]

I found this thread informative. As far as powering a house Lead Acid batteries are still much cheaper and the better quality ones last 16-18 years with care. I don't know that they have achieved that sort of life with Lithium but they probably will fairly soon.

Thanks!

Look up nickel-carbon rechargeable batteries. Those things are long-life and rugged. Not used much anymore from what I can find.

[bangerjim]

And since I guess we can only talk about Ryobi batteries:
The OPs pack has bad cells and needs to be replaced.

OP - - - yes you have a bad worn-out pack. Just buy a new one. Please do not try replacing cells yourself if LiON. If you cannot afford a new one, take it to a battery repair place like Batteries+. They will advise and fix it if possible. And they know what they are doing.